D3320 is the CDT code for endodontic therapy on a premolar (bicuspid) tooth, excluding the final restoration. It covers complete root canal treatment of a premolar, including pulp extirpation, canal preparation, disinfection, and obturation. The crown or other restoration placed after the root canal is billed separately.
Last updated June 2026 ยท Reviewed by the PracticeAlpha billing team
Get help with D3320 claims →Use D3320 when performing complete endodontic therapy on a premolar tooth (teeth 4, 5, 12, 13, 20, 21, 28, or 29 in the Universal Numbering System). The procedure must include complete pulp removal, canal shaping and cleaning, and obturation of all canals. Both first and second premolars are coded D3320. The number of canals does not change the code.
Common clinical scenarios: Premolar with irreversible pulpitis requiring root canal therapy. Premolar with pulp necrosis confirmed by clinical and radiographic findings. Premolar with symptomatic apical periodontitis. Premolar requiring endodontic treatment prior to crown placement. Re-treatment of a previously root canal treated premolar is a separate code (D3346).
Do NOT use D3320 for: Root canal on an anterior tooth - incisors and canines (use D3310). Root canal on a molar tooth (use D3330). Re-treatment of a previously root-canal-treated premolar (use D3346). Pulpotomy as an emergency or interim procedure (use D3220). Root canal on a primary tooth (use D3230 or D3240 for pulpotomy, as full root canal on primary teeth uses different codes).
Most dental plans require pre-authorization for root canal therapy. Submitting a claim after the procedure without prior approval is the most common reason root canal claims are denied. Always verify pre-auth requirements before scheduling treatment. Submit pre-auth with a periapical radiograph and a short narrative explaining the diagnosis.
Using D3320 when the tooth treated is actually a molar or an anterior tooth results in an immediate denial or audit flag. The tooth number on the claim must correspond to a premolar. Teeth 4, 5, 12, 13, 20, 21, 28, and 29 are premolars in the Universal system. A molar (teeth 1-3, 14-16, 17-19, 30-32) must be coded D3330. An anterior tooth (teeth 6-11, 22-27) must be coded D3310.
A pre-operative periapical radiograph showing pathology is required for most payers. The x-ray should demonstrate the clinical reason for root canal therapy, whether apical pathology, deep caries, or canal anatomy. A radiograph that is not diagnostic quality or does not show the full root and periapical region can lead to a denial.
If the clinical notes or radiograph suggest the tooth cannot be restored after the root canal, the payer may deny the procedure as not being in the patient's best interest. If the tooth is restorable, document clearly that a post-treatment restoration is planned. If a crown is placed on a different date, the connection between the root canal and the planned restoration should be established in the record.
Full-length periapical x-ray showing the crown, root, and periapical region of the premolar. The radiograph should demonstrate pathology (apical lesion, deep caries extending to pulp, or other clinical indication) and be of diagnostic quality.
Document working length determination. Payers increasingly want to see evidence of proper canal length determination. A working length x-ray or documented use of an electronic apex locator supports the completeness of the procedure.
A final x-ray showing the completed obturation is standard documentation for any root canal procedure. It confirms all canals were treated to the correct length and that the obturation material is properly placed.
Document the diagnosis (irreversible pulpitis, pulp necrosis, symptomatic apical periodontitis, etc.), the tooth number, the number of canals treated, the irrigants and obturation material used, and the plan for the final restoration.
If pre-auth was obtained, include the authorization number on the claim form. Document the authorization in the patient record as well. Missing this detail is a simple but common cause of delayed payment.
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Learn about our billing servicesD3320 is the CDT code for endodontic therapy (root canal) on a premolar tooth, excluding the final restoration. It covers complete root canal treatment of any premolar, including pulp removal, canal shaping, cleaning, and obturation.
Premolars are the bicuspid teeth between the canines and molars. In the Universal Numbering System, these are teeth 4, 5, 12, 13, 20, 21, 28, and 29. Both first and second premolars on all four quadrants fall under D3320.
No. D3320 excludes the final restoration. A core buildup (D2950) and crown are typically placed after the root canal and must be billed as separate procedures on the claim.
Common reasons: missing pre-authorization, tooth number on the claim does not match a premolar, insufficient radiographic evidence of pathology, tooth identified as non-restorable in clinical notes, or frequency limitation triggered by prior treatment on the same tooth.
D3320 is for premolar root canals. D3330 is for molar root canals. Using D3330 for a premolar or D3320 for a molar is a coding error that triggers denials. The tooth number on the claim must match the tooth type in the code.
Most dental plans require pre-authorization for root canal therapy. Verify the patient's plan requirements before treatment. Submit pre-auth with periapical x-rays and a narrative supporting the diagnosis. Approval before treatment prevents most denials.
Search all 206 CDT codes in our dental coding guide.